#! perl -slw use strict; use GD; GD::Image->trueColor( 1 ); my $im1 = GD::Image->new( $ARGV[ 0 ] ); my $im2 = GD::Image->new( $ARGV[ 1 ] ); my $raw1 = $im1->gd; my $raw2 = $im2->gd; my $xored = $raw1 ^ $raw2; my( $all, $diff ) = (0)x2; $all += 255, $diff += ord substr $xored, $_, 1 for 0 .. length( $xored ) - 1; print $all, ' ', $diff; printf "The simlarity is %.3f%%\n", ( $all - $diff ) / $all * 100; #### C:\test\xx>..\907337 ballons1.jpg ballons2.jpg 672410265 62443267 The simlarity is 90.714% #### C:\test\xx>..\907337 ballons1.jpg ballons1a.jpg 672410265 92011553 The simlarity is 86.316% #### C:\test\xx>..\907337 1.png 2.png 244802805 241803 The simlarity is 99.901% #### C:\test\xx>..\907337 microarray1.jpg microarray2.jpg 340764405 41409302 The simlarity is 87.848%